Electric elevator



QNo Model.)

P. A. PERRETs ELECTRIC ELEVVATUR. No. 510,932. Patented Deo.19,1893.

.wf/" 'p W for; X F j W il l UNITED STATES PATENT OFFICE.

FRANK A. PERRET, OF BROOKLYN, NEW YORK, ASSIGNOR TO THE ELEKTRONMANUFACTURING COMPANY, OF NEV YORK.

ELECTRIC ELEVATOR.

SPECIFICATION forming part of Letters Patent No. 510,932, dated December19, 1893.

Application filed November 12,1892. Serial No. 451,745. (No model.)

To all whom it may concern.-

Be it known that I, FRANK A. PERRET, a citizen of the United States,residing at Brooklyn, in the countyof Kings and State of New York, haveinvented certain new and useful Improvements in Electric Elevators, ofwhich the following is a full, clear, and exact description.

This invention relates chiefiy to that class of elevators, in which aplatform or car is caused to ascend or descend by means of cablesattached thereto, which pass over a pulley or drum at the top of theshaft andthence around a winding drum, which may be located on anyfloor. Such elevators may be divided into two classes: first, those inwhich the speed of hoisting or lowering may be Varied at will by theoperator in the car, this feature being essential in high speedpassenger elevators, as it is necessary to slow down just beforereaching a landing in order to make an accurate stop at the landing,and, second, those elevators in which the speed of the car ispractically constant in both hoisting and lowering oris independent ofthe control of the operator on the car who simply has the power to startthe car either up or down and to stop same. This invention relates tothe latter class. Until recently in nearly all elevators of this classthe winding drums were driven by belts from a constant source of power,the arrangement being such that when the elevator is not in use the beltruns on a loose pulley. Then the operator desired to go up he pulls therope passing through the car in one direction which shifts the belt to atight pulley; pulling the rope back shifts it back to the loose pulleyand stops the car; pulling itin the opposite direction shifts anotherbelt onto the tight pulley which moves the carin the opposite direction.Electric motors have been used in many cases as the sources of power andconnected thus by belts to the elevators, in which case the motor isusually allowed to run constantly, which is wasteful of current, or theattendant has to go to a line switch and shut off the current to stopit, which is inconvenient. In order to avoid these objections, motorshave been coupled direct to the elevator machine and switching deviceshave been connected to the usual operating cord by means of which themotor is stopped, started and reversed.

The invention herein described is concerned with the starting devicesfor the electric motor, and, although the description refers to it inconnection with an electric elevator, it is Well adapted as a motorstarter wherever motors are used, especially for railway motors. In theaccompanying drawings: Figure l vrepresents a general view of theapparatus as applied to an elevator, and Fig. 2 gram of the circuits.

Referring to the drawings by letter, M is an electric motor Which Iprefer to be shunt wound and which is connected to constant potentialmains, L L. I have shown the motor operatively connected to the windingdrum, R of an elevator by a worm G, and a gear wheel G', but theinvention is equally applicable to a spur gear or to a belt connection.S is the brake, which is applied by means of the weight WV, which isadjustable on the lever N. This lever may be lifted and the brakereleased in the old fashioned way by means of a mechanical deviceconnected with the sheave wheel E, around which the operating cable Cpasses, but I prefer to lift the lever N, and release the brake by meansof an electro-magnet or solenoid B, which is connected in the armaturecircuit or preferably in shunt as shown in the diagram. As soon as thecurrent is admitted to the coils of this solenoid it sucks in itsarmature, raises the lever N, and releases the brake. The instant thecircuit is opened at any point, by any means, the solenoid isde-energized, and the Weight IV drops and applies the brake. F is areversing switch, which is preferably actuated by a sheave wheel overwhich the operating cable passes. I prefer that the movable portion ofthis switch should be mounted upon the sheave wheel while the two setsof clips O and P, with which it makes contact, are stationary. Fig. lshows this switch at its central position, at which point both armatureand field circuits are open. A pull on the cable in one direction closesboth field and armature circuits and causes rotation of the drum in onedirection. A pull on the cable in the other direction closes both fieldand armature circuits and, as the armature is a dia- IOO circuit is'reversed, produces rotation in the Opposite direction. Each set of theclips of this switch. consists of six contact points, three beingarranged on each side of ablock of insulating material, and there willbe four metallic blades f pivoted to a block of insulating material fcarried bythe sheave. Two of these blades are supposed to be directlybehind the two shown in Fig. 1. The two blades standing to the right areadapted to make contact with the six clips O, one blade connecting threeclips and the other blade the other three clips. The same arrangementoccurs on the left handside.

-H is a rheostat which is connected in the armature circuit. The diagramshows the brush on the lowest contacts at which points all theresistance is in circuit, and there should be sufcient 'resistance toprotect the armature when at rest from ya current in eX- cess of itssafe carrying capacity. The contact brush of this rheostat is attachedto the armature ofthesolenoid A, which is connected in a direct shunt tothe brushes of the motor, theresistance I-I being outside of theterminals of the shunt. Hence little or no current will flow through thesolenoid until the armature commences to turn and to generate acounter-electrc-motive force. Then the current in the solenoid willincrease in proportion to theincrease of counter-electro-motive forcegenerated by the armature and will not be affected in any way by thecondition of the rheostat. The solenoid therefore is controlled entirelyand only by the difference of potential between the positive andnegative sides vof the motor armature.

v We will now suppose the switch F to be open, as shown, and that theoperator pulls the cable to start the mechanism. This closes the switchF, and the circuit is at once made through the tield magnets andarmature `of the motor, the rheostat H, its solenoid A,'and the brakesolenoid B. The circuits are traced as follows: Referring to Fig. 2, thedotted lines indicate the two right hand blades f thrown into contactwith the two groups O of. three clips each. When the switch is in thisposition the current is led from the positiveV line to vclip 1, thenceto clip 2, along the switch bladeto clip 3, thence by wired through thearmature of the motor, wire 5, rheostat H, wi re 6, clip 7, switchblade, clip 8, wire 9 tothe'negativemain. Thelieldmagneticcircuitbranches at clip 3 and isled through the switch blade toclip 10, thence by wire 1l, wire12, through the ield magnet, wire13,wire14, clip 15, andjoins the armature 'circuit at clip 7. Thebrake solenoidB is connected in wire 16 across the armature and outside of therheostat H. The controlling solenoid A isin circuit 17 directly acrossthe brushes of the motor. The brake solenoid instantly attracts thearmature, raises the weight W, and releases the brake. Unless there isan excessiveloadon 'the lcar the armature will commence at once torevolve, will vaccelerate rapidly, the counterelectro-motive forcegenerated by it will increase and the current through the solenoid Awill increase correspondingly, causing it to draw up its armature withincreasing power thereby moving the contact brush across the row ofcontacts on the rheostat, and cutting out resistance step bystep untilit reaches the top where the resistance is all out, and the motor isrunning at full speed.

In case there should be an excessive load on the car or it is preventedfrom moving v freely, the current, which is at first admitted to ,thearmature through the rheostat, will not start the motor; consequently,the solenoid A, will receive practically no current, and will not'attract its armature with suiicient power to' move the contact brush'onthe rheostat. Consequently, no resistance 'will be cut out. The operatorseeing that the motor does not start, will open his switch, and willhunt up the trouble, or if it is overloaded will ask somebody to step'out.

The` solenoid will work against gravity, preferably, so that the Weightof its armature will resist the'small pull of the' coil due to thelittle current which may flow through it while themotor armature isstationary; or a spring may be used to accomplish the Vsame thing. hrepresents a dash pot or air cushion of any suitable construction, used,it necessary, to prevent the` too rapid 'movement' `of th'e solenoidarmature.

We'will now suppose the mechanism vto have been put into operation asalready described, and that a stop is to be made. .The operator pullsthe cord until the switch reaches the centralpoint where a stop i willprevent its going farther, until thel contact brush of the rheostat hasdroppedv again' to the bottom and all the resistance' is inv circuit.This stop vis held against the periphery'ot the switch wheel lwhile the'motor is running, but when the wheel is moved to the middle position-tostop 'the motor, it falls into the notch andlocks the wheel until'it'isremoved therefrom by the endrof the resistance'controlling arm when itreaches the point where all-the resistance is in circuit. This preventsreversing until the resistance is put in. As soon as the circuit has'been broken at the switch F as just described, the solenoid B isde-energized andthe brake is applied. It. will be seen that thisprinciple of controlling the starting of the motor by thecounterelectro-motive torce generated by the motor armature is',applicable to 'motors driving railway vcars or any other apparatus andisa sure protectionto the motor.

Having described my invention, I claime- 1. An electric motor having amainor armature circuit and a shunt or field circuit, and a rheostat inthe armature circuit,^'in

combination with a third ycircuit including an electro-responsivevapparatus controlling kthe rheostat, said third circuitA being a'directICO IIO

shunt to the'brushes of the motor, substanlocking device substantiallyas and for the tia'lly as described. purpose set forth. 1o

2. The combination, of an electric motor In testimony whereof Isubscribe my sigand its circuit, an electric switch controlling naturein presence of two Witnesses.

5 said circuit, a locking device for said switch FRANK A. PERRET.

when in its open position, a rheost-at in Witnesses: the motor circuitand an electro responsive WM. A. ROSENBAUM,

apparatus operating the rheostat and the said JOS. J. UHL.

